Backing up computers is an important task in the everyday operation of computer systems. Backup may be required for retrieval of information in cases of human errors, technical failures, upgrades, or the like, as well as for legal or operational reasons.
Traditionally, systems used tapes for storing large amounts of data. Tapes are reliable and are considered environmentally friendly, i.e., do not waste energy unlike disks that spin constantly and consume energy. However, tapes have some significant drawbacks. For example, they take up a lot of physical space, and retrieving data from tapes may take a long time, for example in the order of magnitude of minutes, as compared to milliseconds in disks.
In addition, handling tapes necessitates manual labor. For example, operations such as making copies of tapes have to be done manually, creating backups at off-site locations cannot be performed without physically transporting them, or the like.
Further, when keeping data on tapes for long periods of time, such as years or decades, supporting tape drives have to be maintained in order to retrieve data from the tape when required. This drawback also implies that upgrading the used tape drive technology may be a complex operation.
Mainframe (MF) computers in general, and specifically those using the z/OS operating system, use disk storage for live or active data, but cannot use disk storage for backup or for archiving large amounts of data.
Some systems use virtual tapes for backing up mainframe computers. Virtual tapes are the same as physical tapes from the point of view of the MF operating system, while the data is physically written to disks and not to tapes. However, a virtual tape solution is still subject to the same limitations related to the number of mainframes that can connect or communicate with a storage device, and have to comply with the MF data protocols in order to emulate tape drives for the MF operating system. The same drawbacks are valid also for any storage equipment connecting to the MF.
US2005038830 discloses a method of distributing mainframe software and data using PC-based data media, comprising a mainframe program for converting a mainframe sequential dataset or all or part of a mainframe library of texts or load modules to a sequential dataset of fixed length records and for reverting these converted records to its original form in the same or another mainframe data center, and procedures for downloading the converted mainframe data to a PC and uploading the PC file to a mainframe. Keeps a file record in the MF, we receive in memory and immediately send out
US2003088720 discloses a heterogeneous computer system, a heterogeneous input/output system and a data back-up method for the systems. An I/O subsystem A for open system and an I/O subsystem B for a mainframe are connected by a communication unit. In order to back up the data from at least a disk connected to the I/O subsystem B in a MT library system and in order to permit the mainframe to access the data in the I/O subsystem B, the I/O subsystem A includes a table for assigning a vacant memory address in a local subsystem to the memory of the I/O subsystem for an open system. A request of variable-length record format received from the mainframe is converted into a fixed-length record format for the subsystem B. The disk designated according to the table is accessed, and the data thus obtained is sent to the mainframe and backed up in the back-up system.
US2007271302 discloses various data copy systems and methods for use in a disaster recovery network architecture including first, second and third computers and various datalinks coupling the first, second and third computers together. One embodiment of such a method includes: (1) transferring the data from the first computer to the second computer, (2) transferring the data from the second computer to the third computer only after the transferring the data from the first computer to the second computer is complete and (3) deleting the data from the second computer only after the transferring the data from the second computer to the third computer is complete.
U.S. Pat. No. 6,772,365B discloses a mainframe system disk control unit provided with apparatus for accessing open system storage connected to a SAN and apparatus for converting the input and output data format to that of the open system, and the mainframe is made to access a volume of open system storage in the same manner to a volume under control of the mainframe system disk control unit. Thus, data in the open system storage is backed up to the mainframe system. Communication is performed between the program on the mainframe and the program on the open system host computer, and prior to starting backup, the updating of data in the open system storage system is prohibited.
US2004044803 discloses a storage control apparatus comprising: a storage area A where data is stored according to a recording format alpha, the format alpha being a format in which an open computer reads/writes data; a storage area B where data is stored according to a recording format beta, the format beta being a format in which a mainframe computer reads/writes data; a data input/output unit x for receiving a data input/output request from the open computer, and inputting/outputting data to/from the storage area A in response to the request; a data input/output unit y for receiving a data input/output request from the mainframe computer, and inputting/outputting data to/from the storage area B in response to the request; and a data recording format conversion unit X capable of storing data stored in the storage area A according to the format alpha into the data storage area B according to the format beta.
US2004088507 relates to a computer system that includes a first computer, a second computer, a first storage apparatus storing data in a fixed-length block format used by the second computer, and a backup apparatus connected to the first computer and storing data in a variable-length block format, the present invention provides a backup method for backing up data stored in the first storage apparatus to the backup apparatus. The first computer sends the second computer a request to read data in the fixed-length block format. In response to this request, the second computer reads the fixed-length block format data from the first storage apparatus and transfers this data to the first computer. The first computer converts the transferred fixed-length block format data into variable-length block format data. The converted variable-length block format data is stored in the backup apparatus.
JP2004220484A relates to the problem of backing up the data of a main frame stored in a storage device connected only to the main frame in an open type backup device in a computer system with the main frame and an open type server. The disclosed solution is: when the data of the main frame stored in a first storage device connected to only the main frame is backed up, at first, a backup means in the side of the main frame stores a backup object file in the file stored in the first storage device in a second storage device connected to both of the main frame 100 and the open-type server. Then, a backup means in the side of the open-type server stores the backup object file stored in the second storage device 301 in a backup device.